Neptune revolves round the sun in about 172 years, at a mean distance of thirty,--that of Uranus being nineteen, and that of the earth one: and by its discovery the solar system has been extended _one thousand millions of miles_ beyond its former limit.
Neptune is suspected to have a ring, but the suspicion has not been confirmed. It has been demonstrated by the observations of Mr. Lassell, M. Otto Struve, and Mr. Bond, to be attended by at least one satellite.
One of the most curious facts brought to light by the discovery of Neptune, is the failure of Bode’s law to give an approximation to its distance from the sun; a striking exemplification of the danger of trusting to the universal applicability of an empirical law. After standing the severe test which led to the discovery of the asteroids, it seemed almost contrary to the laws of probability that the discovery of another member of the planetary system should prove its failure as an universal rule.
Although Comets have a smaller mass than any other cosmical bodies--being, according to our present knowledge, probably not equal to 1/5000th part of the earth’s mass--yet they occupy the largest space, as their tails in several instances extend over many millions of miles. The cone of luminous vapour which radiates from them has been found in some cases (as in 1680 and 1811) equal to the length of the earth’s distance from the sun, forming a line that intersects both the orbits of Venus and Mercury. It is even probable that the vapour of the tails of comets mingled with our atmosphere in the years 1819 and 1823.--_Humboldt’s Cosmos_, vol. i.
COMETS VISIBLE IN SUNSHINE--THE GREAT COMET OF 1843.
The phenomenon of the tail of a Comet being visible in bright Sunshine, which is recorded of the comet of 1402, occurred again in the case of the large comet of 1843, whose nucleus and tail were seen in North America on February 28th (according to the testimony of J. G. Clarke, of Portland, State of Maine), between one and three o’clock in the afternoon. The distance of the very dense nucleus from the sun’s light admitted of being measured with much exactness. The nucleus and tail (a darker space intervening) appeared like a very pure white cloud.--_American Journal of Science_, vol. xiv.